X-ray tubes are typically constructed as high-vacuum tubes. Because of the high vacuum, sparkovers, and the resultant short circuit, between the cathode and the anode of the X-ray tube when the X-ray voltage, which is in the kilovolt range, is applied are fundamentally prevented. Slight quantities of residual gases, which contaminate the high vacuum, however, are unavoidable. This is true particularly because over the course of operation of the X-ray tube, gaseous ingredients of material emerge in the interior of the tube. The residual gases can be ionized by the X-ray voltage. The ionization may cause a sparkover and thus the short circuit inside the X-ray tube.
The courses over time of the short-circuit currents and the resultant events for charge compensation in the lines of the high-voltage supply sometimes have very steep flanks, since they proceed very quickly. The resultant interference spectrum therefore extends into the upper megahertz range and is extremely broadbanded. Moreover, the short-circuit currents and charge compensation currents cause vibrations associated with over-voltages, and these vibrations fade only very slowly.
Because of such interference signals and over-voltages in the high-voltage circuit of the X-ray device, problems in the function of the electronics and the computer system can occur. Often, component failures also occur, above all in the high-voltage circuit of the high voltage generator. Besides the downtimes in operation and expensive damage to the X-ray device, these problems also cause an increased radiation exposure to patients to be examined, who because of system failures must be examined repeatedly.